Earth History & Evolution Flashcards

Vocabulary flashcards generated from the Earth History & Evolution lecture notes covering geological time, extinction events, biological evolution, and Earth's formation.

Four Levels of Geologic Time

The structural hierarchy of geologic time consisting of Eon, Era, Period, and Epoch.

Paleozoic Periods

The six periods comprising the Paleozoic era: Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian.

Mesozoic Periods

The three periods comprising the Mesozoic era: Triassic, Jurassic, and Cretaceous.

Cenozoic Epochs

The major epochs comprising the Cenozoic era: Paleocene, Eocene, Oligocene, Miocene, Pliocene, Pleistocene, and Holocene.

End-Permian Extinction

The largest mass extinction in Earth history, occurring at approximately $252\,Ma$.

K-Pg Extinction

Mass extinction caused by a large asteroid impact at Chicxulub, which resulted in severe environmental disruption.

Late Ordovician Extinction

Mass extinction caused by major glaciation, sea-level fall, habitat loss, and subsequent rapid environmental change.

Sedimentary Environment

A specific setting where sediment is transported and deposited.

Cross-Bedding

A sedimentary feature that indicates the movement of sediment by flowing water or wind.

Mud Cracks

Sedimentary structures indicating that sediment was originally wet, exposed to the air, and dried out.

Trace Fossils

Fossil evidence of organism behavior, such as footprints, tracks, or burrows.

Biological Species Concept

A species definition stating that a species is a group of populations whose members can interbreed and produce fertile offspring.

Evolution

The change in heritable characteristics of biological populations across successive generations.

Conditions for Natural Selection

The three required conditions for natural selection: phenotypic variation, heritability, and differential reproductive success.

Adaptation

A heritable trait that is favored because it increases an organism's fitness in a given environment.

Sexual Selection

A mode of natural selection based on differences in mating success among individuals.

Genetic Drift

Random changes in allele frequencies within a population, which exert the strongest effect in small populations.

Mutation

An evolutionary process that creates new genetic variation.

Gene Flow

The transfer or movement of alleles between different populations.

Speciation

The evolutionary process by which new biological species arise.

Allopatric Speciation

Speciation caused by the geographic separation and isolation of populations.

Reproductive Isolation

Biological or behavioral barriers that prevent gene flow between distinct populations.

Ring Species

A connected chain of neighboring populations where adjacent groups can interbreed, but the two terminal end populations cannot.

Evo-Devo

Evolutionary Developmental Biology; the study of how changes in developmental processes produce evolutionary changes in organismal form.

Hox Genes

A group of developmental genes that control body-region identity and spatial organization along the body axis during development.

Heterochrony

An evolutionary change in the timing or rate of developmental events.

Paedomorphosis

A developmental outcome where an adult organism retains characteristics that were juvenile in its ancestors.

Peramorphosis

A developmental outcome where adult development extends beyond the state observed in the ancestral adult condition.

Planetary Accretion

The growth of planets through successive collisions and gravitational accumulation of matter.

Compositional Layers of Earth

Earth's four main compositional divisions: crust, mantle, outer core, and inner core.

Volcanic Outgassing

The release of trapped gases (such as water vapor, $CO_2$, and $N_2$) from Earth's interior during volcanic activity, establishing the early atmosphere.

Zircons

Durable minerals that preserve early geochemical information and can be dated using uranium-lead isotopic decay.

Greenstone Belts

Ancient sequences of metamorphosed volcanic and sedimentary rocks critical for studying early Earth geology.

Continental Accretion

The process by which crustal fragments are added to a growing continental mass.

Craton

An ancient, stable, and tectonically quiet core region of a continent.

Banded Iron Formations (BIFs)

Layered sedimentary rocks composed of alternating iron- and silica-rich layers that document changes in ocean chemistry and free oxygen accumulation.

Endosymbiotic Theory

The theory that eukaryotic organelles like mitochondria and chloroplasts originated as free-living prokaryotic bacteria engulfed by ancestral host cells.

Biological Diversity

The total number or variety of species or taxonomic groups in a given system.

Disparity

The range or degree of morphological difference among distinct organisms.

Terrestrial Plant Adaptations

Key evolutionary traits that enabled plant survival on land, including cuticles, stomata, vascular tissue, roots, seeds, and pollen.

Fitness

An organism's relative reproductive success and overall contribution of offspring to future generations.